X is the main protagonist of the Mega Man X series and serves as a guide in the Mega Man Zero series. He was created as a successor to the original Mega Man by Dr. Thomas Light and was considered to be his ultimate creation. X was the first robot to have what was essentially free will. Because of how dangerous this could be, Dr. Light sealed X in a stasis capsule in order to perform system tests and AI which would take 30 years to fully complete. 100 years later, a scientist named Dr. Cain found the capsule and based on X's design specifications began creating a new series of robots called Reploids. However, since these robots did not go through the same extensive testing as X had gone through, some of them ended up becoming violent and aggressive. These robots were labeled as Mavericks. X, feeling responsible for this, decided to join the Maverick Hunters. He became one of the best Maverick Hunters to have ever existed and teamed up with Zero and Axl to keep the world at peace and prevent conflict between Reploids and humans.